Working medium and heat cycle system

ABSTRACT

To provide a working medium for heat cycle which has less influence over the ozone layer, which has less influence over global warming and which provides a heat cycle system excellent in the cycle performance (the efficiency and the capacity), and a heat cycle system excellent in the cycle performance (the efficiency and the capacity). A working medium for heat cycle comprising 1,2-difluoroethylene is employed for a heat cycle system (such as a Rankine cycle system, a heat pump cycle system, a refrigerating cycle system  10  or a heat transport system).

This is a continuation of application Ser. No. 16/504,615, filed Jul. 8,2019, which is a continuation of application Ser. No. 15/704,211, filedSep. 14, 2017, now U.S. Pat. No. 10,392,544, which is a continuation ofapplication Ser. No. 14/084,066, filed Nov. 19, 2013, now U.S. Pat. No.9,790,412, which is a continuation of International application no.PCT/JP2012/062844, filed May 18, 2012, which claimed priority toJapanese patent application no. 2011-112416, filed May 19, 2011, ofwhich all of the disclosures are incorporated herein by reference intheir entireties.

TECHNICAL FIELD

The present invention relates to a working medium and a heat cyclesystem employing the working medium.

BACKGROUND ART

Heretofore, as a working medium for heat cycle such as a coolant for arefrigerator, a coolant for an air conditioner, a working fluid forpower generation system (such as exhaust heat recovery powergeneration), a working medium for a latent heat transport apparatus(such as a heat pipe) or a secondary cooling medium, achlorofluorocarbon (CFC) such as chlorotrifluoromethane ordichlorodifluoromethane or a hydrochlorofluorocarbon (HCFC) such aschlorodifluoromethane has been used. However, influences of CFCs andHCFCs over the ozone layer in the stratosphere have been pointed out,and their use are regulated at present.

Accordingly, as a working medium for heat cycle, a hydrofluorocarbon(HFC) which has less influence over the ozone layer, such asdifluoromethane (HFC-32), tetrafluoroethane or pentafluoroethane, hasbeen used. However, it is pointed out that HFCs may cause globalwarming. Accordingly, development of a working medium for heat cyclewhich has less influence over the ozone layer and has a low globalwarming potential is an urgent need.

For example, 1,1,1,2-tetrafluoroethane (HFC-134a) used as a coolant foran automobile air conditioner has a global warming potential so high as1,430 (100 years). Further, in an automobile air conditioner, thecoolant is highly likely to leak out to the air e.g. from a connectionhose or a bearing.

As a coolant which replaces HFC-134a, carbon dioxide and1,1-difluoroethane (HFC-152a) having a global warming potential of 124(100 years) which is low as compared with HFC-134a, have been studied.

However, with carbon dioxide, the equipment pressure tends to beextremely high as compared with HFC-134a, and accordingly there are manyproblems to be solved in application to all the automobiles. HFC-152ahas a range of inflammability, and has a problem for securing thesafety.

As a working medium for heat cycle which has less influence over theozone layer and has less influence over global warming, ahydrofluoroolefin (HFO) having a carbon-carbon double bond which iseasily decomposed by OH radicals in the air is conceivable.

As a working medium for heat cycle comprising a HFO, for example, thefollowing have been known.

(1) 3,3,3-Trifluoropropene (HFO-1243zf), 1,3,3,3-tetrafluoropropene(HFO-1234ze), 2-fluoropropene (HFO-1261yf), 2,3,3,3-tetrafluoropropene(HFO-1234yf) and 1,1,2-trifluoropropene (HFO-1243yc) (Patent Document1).

(2) 1,2,3,3,3-Pentafluoropropene (HFO-1225ye),trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)),cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)) and HFO-1234yf (PatentDocument 2).

However, each of HFOs in (1) is insufficient in the cycle performance(capacity).

Each of HFOs in (2) is also insufficient in the cycle performance(capacity).

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-A-04-110388-   Patent Document 2: JP-A-2006-512426

DISCLOSURE OF INVENTION Technical Problem

The present invention provides a working medium for heat cycle, whichhas less influence over the ozone layer, which has less influence overglobal warming and which provides a heat cycle system excellent in thecycle performance (efficiency and capacity), and a heat cycle systemexcellent in the cycle performance (efficiency and capacity).

Solution to Problem

The present invention provides a working medium for heat cycle(hereinafter sometimes referred to as working medium), which comprises1,2-difluoroethylene (hereinafter sometimes referred to as HFO-1132).

The working medium of the present invention preferably further containsa hydrocarbon.

The working medium of the present invention preferably further containsa HFC.

The working medium of the present invention preferably further containsa hydrochlorofluoroolefin (HCFO) or a chlorofluoroolefin (CFO).

The heat cycle system of the present invention employs the workingmedium of the present invention.

Advantageous Effects of Invention

The working medium of the present invention, which comprises HFO-1132having a carbon-carbon double bond which is easily decomposed by OHradicals in the air, has less influence over the ozone layer and hasless influence over global warming.

The heat cycle system of the present invention, which employs theworking medium of the present invention excellent in the thermodynamicproperties due to HFO-1132, is excellent in the cycle performance(efficiency and capacity). Further, due to excellent efficiency, areduction in the power consumption will be attained, and due toexcellent capacity, downsizing of a system can be achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic construction view illustrating an example of arefrigerating cycle system.

FIG. 2 is a cycle diagram illustrating the state change of a workingmedium in a refrigerating cycle system on a temperature-entropy chart.

FIG. 3 is a cycle diagram illustrating the state change of a workingmedium in a refrigerating cycle system on a pressure-enthalpy chart.

DESCRIPTION OF EMBODIMENTS <Working Medium>

The working medium of the present invention comprises1,2-difluoroethylene.

The working medium of the present invention may contain, as the caserequires, another working medium which will be gasified or liquefiedtogether with HFO1132, such as a hydrocarbon, a HFC, a HCFO, a CFO orother HFO. Further, the working medium of the present invention may beused in combination with a component other than the working medium, usedtogether with the working medium (hereinafter, a composition containingthe working medium and a component other than the working medium will bereferred to as a working medium-containing composition). The componentother than the working medium may, for example, be a lubricating oil, astabilizer, a leak detecting substance, a desiccating agent or otheradditives.

(HFO-1132)

As HFO-1132, there are two stereoisomers of trans-1,2-difluoroethylene(HFO-1132(E)) and cis-1,2-difluoroethylene (HFO-1132(Z)). In the presentinvention, HFO-1132(E) may be used alone, HFO-1132(Z) may be used alone,or a mixture of HFO-1132(E) and HFO-1132(Z) may be used.

The content of HFO-1132 is preferably at least 60 mass %, morepreferably at least 70 mass %, further preferably at least 80 mass %,particularly preferably 100 mass % in the working medium (100 mass %).

(Hydrocarbon)

The hydrocarbon is a working medium component which improves solubilityof the working medium in a mineral lubricating oil.

The hydrocarbon has preferably from 3 to 5 carbon atoms, and may belinear or branched.

The hydrocarbon is specifically preferably propane, propylene,cyclopropane, butane, isobutane, pentane or isopentane.

The hydrocarbons may be used alone or in combination of two or more.

The content of the hydrocarbon is preferably from 1 to 30 mass %, morepreferably from 2 to 30 mass %, in the working medium (100 mass %). Whenthe content of the hydrocarbon is at least 1 mass %, the solubility ofthe lubricating oil in the working medium will sufficiently be improved.

(HFC)

The HFC is a working medium component which improves the cycleperformance (capacity) of a heat cycle system.

The HFC is preferably a HFC which has less influence over the ozonelayer and which has less influence over global warming.

The HFC has preferably from 1 to 5 carbon atoms, and may be linear orbranched.

The HFC may, for example, be specifically difluoromethane,difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane,pentafluoropropane, hexafluoropropane, heptafluoropropane,pentafluorobutane or heptafluorocyclopentane. Among them, particularlypreferred is difluoromethane (HFC-32), 1,1-difluoroethane (HFC-152a),1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane(HFC-134a) or pentafluoroethane (HFC-125), which has less influence overthe ozone layer and which has less influence over global warming.

The HFCs may be used alone or in combination of two more.

The content of the HFC in the working medium (100 mass %) is preferablyfrom 1 to 99 mass %, more preferably from 1 to 60 mass %. For example,in a case where the HFC is HFC-125, it is possible to suppress adecrease in the coefficient of performance and to remarkably improve therefrigerating capacity within a content range of from 1 to 60 mass %. Inthe case of HFC-134a, it is possible to improve the refrigeratingcapacity without a decrease in the coefficient of performance, within acontent range of from 1 to 40 mass %. Further, in the case of HFC-32, itis possible to suppress a decrease in the coefficient of performance andto remarkably improve the refrigerating capacity within a content rangeof from 1 to 99 mass %. Improvement is possible depending upon therequired properties of the working medium.

(HCFO, CFO)

The HCFO and the CFO are working medium components which suppresscombustibility of the working medium. Further, they are components whichimprove the solubility of the lubricating oil in the working medium.

As the HCFO and the CFO, preferred is a HCFO which has less influenceover the ozone layer and which has less influence over global warming.

The HCFO has preferably from 2 to 5 carbon atoms, and may be linear orbranched.

The HCFO may, for example, be specifically hydrochlorofluoropropene orhydrochlorofluoroethylene. Among them, particularly preferred is1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) or1-chloro-1,2-difluoroethylene (HCFO-1122), with a view to sufficientlysuppressing combustibility of the working medium without substantiallydecreasing the cycle performance (capacity) of the heat cycle system.

The HCFOs may be used alone or in combination of two or more.

The CFO has preferably from 2 to 5 carbon atoms, and may be linear orbranched.

The CFO may, for example, be specifically chlorofluoropropene orchlorofluoroethylene. Among them, particularly preferred is1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya) or1,2-dichloro-1,2-difluoroethylene (CFO-1112) with a view to sufficientlysuppressing combustibility of the working medium without substantiallydecreasing the cycle performance (capacity) of the heat cycle system.

The total content of the HCFO and the CFO is preferably from 1 to 60mass %, more preferably from 1 to 40 mass % in the working medium (100mass %). When the total content of the HCFO and the CFO is from 1 to 40mass %, it is possible to sufficiently suppress combustibility of theworking medium without substantially decreasing the cycle performance(capacity) of the heat cycle system.

(Other HFO)

Other HFO is preferably a HFO which has less influence over the ozonelayer and which has less influence over global warming.

Such other HFO may, for example, be HFO-1224ye, HFO-1234ze orHFO-1243zf.

(Lubricating Oil)

As the lubricating oil to be used for the working medium-containingcomposition, a known lubricating oil used for the heat cycle system maybe used.

The lubricating oil may, for example, be an oxygen-containing syntheticoil (such as an ester lubricating oil or an ether lubricating oil), afluorinated lubricating oil, a mineral oil or a hydrocarbon syntheticoil.

The ester lubricating oil may, for example, be a dibasic acid ester oil,a polyol ester oil, a complex ester oil or a polyol carbonate oil.

The dibasic acid ester oil is preferably an ester of a C₅₋₁₀ dibasicacid (such as glutaric acid, adipic acid, pimelic acid, suberic acid,azelaic acid or sebacic acid) with a C monohydric alcohol which islinear or has a branched alkyl group (such as methanol, ethanol,propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol,decanol, undecanol, dodecanol, tridecanol, tetradecanol orpentadecanol). Specifically, ditridecyl glutarate, di(2-ethylhexyl)adipate, diisodecyl adipate, ditridecyl adipate or di(3-ethylhexyl)sebacate may, for example, be mentioned.

The polyol ester oil is preferably an ester of a diol (such as ethyleneglycol, 1,3-propanediol, propylene glycol, 1,4-butanediol,1,2-butandiol, 1,5-pentadiol, neopentyl glycol, 1,7-heptanediol or1,12-dodecanediol) or a polyol having from 3 to 20 hydroxy groups (suchas trimethylolethane, trimethylolpropane, trimethylolbutane,pentaerythritol, glycerol, sorbitol, sorbitan or sorbitol/glycerincondensate) with a C₆₋₂₀ fatty acid (such as a linear or branched fattyacid such as hexanoic acid, heptanoic acid, octanoic acid, nonanoicacid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acidor oleic acid, or a so-called neo acid having a quaternary a carbonatom).

The polyol ester oil may have a free hydroxy group.

The polyol ester oil is preferably an ester (such as trimethylolpropanetripelargonate, pentaerythritol 2-ethylhexanoate or pentaerythritoltetrapelargonate) of a hindered alcohol (such as neopentyl glycol,trimethylolethane, trimethylolpropane, trimethylolbutane orpentaerythritol).

The complex ester oil is an ester of a fatty acid and a dibasic acid,with a monohydric alcohol and a polyol. The fatty acid, the dibasicacid, the monohydric alcohol and the polyol may be as defined above.

The polyol carbonate oil is an ester of carbonic acid with a polyol.

The polyol may be the above-described diol or the above-describedpolyol. Further, the polyol carbonate oil may be a ring-opening polymerof a cyclic alkylene carbonate.

The ether lubricating oil may be a polyvinyl ether oil or apolyoxyalkylene lubricating oil.

The polyvinyl ether oil may be one obtained by polymerizing a vinylether monomer such as an alkyl vinyl ether, or a copolymer obtained bycopolymerizing a vinyl ether monomer and a hydrocarbon monomer having anolefinic double bond.

The vinyl ether monomers may be used alone or in combination of two ormore.

The hydrocarbon monomer having an olefinic double bond may, for example,be ethylene, propylene, various forms of butene, various forms ofpentene, various forms of hexene, various forms of heptene, variousforms of octene, diisobutylene, triisobutylene, styrene, α-methylstyreneor alkyl-substituted styrene. The hydrocarbon monomers having anolefinic double bond may be used alone or in combination of two or more.

The polyvinyl ether copolymer may be either of a block copolymer and arandom copolymer.

The polyvinyl ethers may be used alone or in combination of two or more.

The polyoxyalkylene lubricating oil may, for example, be apolyoxyalkylene monool, a polyoxyalkylene polyol, an alkyl ether of apolyoxyalkylene monool or a polyoxyalkylene polyol, or an ester of apolyoxyalkylene monool or a polyoxyalkylene polyol. The polyoxyalkylenemonool or the polyoxyalkylene polyol may be one obtained by e.g. amethod of subjecting a C₂₋₄ alkylene oxide (such as ethylene oxide orpropylene oxide) to ring-opening addition polymerization to maninitiator such as water or a hydroxy group-containing compound in thepresence of a catalyst such as an alkali hydroxide. Further, onemolecule of the polyoxyalkylene chain may contain single oxyalkyleneunits or two or more types of oxyalkylene units. It is preferred that atleast oxypropylene units are contained in one molecule.

The initiator may, for example, be water, a monohydric alcohol such asmethanol or butanol, or a polyhydric alcohol such as ethylene glycol,propylene glycol, pentaerythritol or glycerol.

The polyoxyalkylene lubricating oil is preferably an alkyl ether or anester of a polyoxyalkylene monool or polyoxyalkylene polyol. Further,the polyoxyalkylene polyol is preferably a polyoxyalkylene glycol.Particularly preferred is an alkyl ether of a polyoxyalkylene glycolhaving the terminal hydroxy group of the polyoxyalkylene glycol cappedwith an alkyl group such as a methyl group, which is called a polyglycoloil.

The fluorinated lubricating oil may, for example, be a compound havinghydrogen atoms of a synthetic oil (such as the after-mentioned mineraloil, poly-α-olefin, alkylbenzene or alkylnaphthalene) substituted byfluorine atoms, a perfluoropolyether oil or a fluorinated silicone oil.

The mineral oil may, for example, be a naphthene mineral oil or aparaffin mineral oil obtained by purifying a lubricating oil fractionobtained by atmospheric distillation or vacuum distillation of crude oilby a purification treatment (such as solvent deasphalting, solventextraction, hydrocracking, solvent dewaxing, catalytic dewaxing,hydrotreating or clay treatment) optionally in combination.

The hydrocarbon synthetic oil may, for example, be a poly-α-olefin, analkylbenzene or an alkylnaphthalene.

The lubricating oils may be used alone or in combination of two or more.

The lubricating oil is preferably a polyol ester oil and/or a polyglycoloil in view of the compatibility with the working medium, particularlypreferably a polyalkylene glycol oil with a view to obtaining aremarkable antioxidant effect by a stabilizer.

The content of the lubricating oil is not limited within a range not toremarkably decrease the effects of the present invention, variesdepending upon e.g. the application and the form of a compressor, and ispreferably from 10 to 100 parts by mass, more preferably from 20 to 50parts by mass based on the working medium (100 parts by mass).

(Stabilizer)

The stabilizer to be used for the working medium-containing compositionis a component which improves the stability of the working mediumagainst heat and oxidation.

The stabilizer may, for example, be an oxidation resistance-improvingagent, a heat resistance-improving agent or a metal deactivator.

The oxidation resistance-improving agent and the heatresistance-improving agent may, for example, beN,N′-diphenylphenylenediamine, p-octyldiphenylamine,p,p′-dioctyldiphenylamine, N-phenyl-1-naphthyamine,N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine,di-1-naphthylamine, di-2-naphthylamine, N-alkylphenothiazine,6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol,4-methyl-2,6-di-(t-butyl)phenol or4,4′-methylenebis(2,6-di-t-butylphenol). The oxidationresistance-improving agents and the heat resistance-improving agents maybe used alone or in combination of two or more.

The metal deactivator may, for example, be imidazole, benzimidazole,2-mercaptobenzothiazole, 2,5-dimercaptothiadiazole,salicylysine-propylenediamine, pyrazole, benzotriazole, tritriazole,2-methylbenzamidazole, 3,5-dimethylpyrazole, methylenebis-benzotriazole,an organic acid or an ester thereof, a primary, secondary or tertiaryaliphatic amine, an amine salt of an organic acid or inorganic acid, aheterocyclic nitrogen-containing compound, an amine salt of an alkylphosphate, or a derivative thereof.

The content of the stabilizer is not limited within a range not toremarkably decrease the effects of the present invention, and ispreferably at most 5 mass %, more preferably at most 1 mass % in theworking medium-containing composition (100 mass %).

(Leak Detecting Substance)

The leak detecting substance to be used for the workingmedium-containing composition may, for example, be an ultravioletfluorescent dye, an odor gas or an odor masking agent.

The ultraviolet fluorescent dye may be known ultraviolet fluorescentdyes as disclosed in e.g. U.S. Pat. No. 4,249,412, JP-A-10-502737,JP-A-2007-511645, JP-A-2008-500437 and JP-A-2008-531836.

The odor masking agent may be known perfumes as disclosed in e.g.JP-A-2008-500437 and JP-A-2008-531836.

In a case where the leak detecting substance is used, a solubilizingagent which improves the solubility of the leak detecting substance inthe working medium may be used.

The solubilizing agent may be ones as disclosed in e.g. JP-A-200T511645,JP-A-2008-500437 and JP-A-2008-531836.

The content of the leak detecting substance is not particularly limitedwithin a range not to remarkably decrease the effects of the presentinvention, and is preferably at most 2 mass %, more preferably at most0.5 mass % in the working medium-containing composition (100 mass %).

(Other Compound)

The working medium of the present invention and the workingmedium-containing composition may contain a C₁₋₄ alcohol or a compoundused as a conventional working medium, coolant or heat transfer medium(hereinafter the alcohol and the compound will generally be referred toas other compound).

As such other compound, the following compounds may be mentioned.

Fluorinated ether: Perfluoropropyl methyl ether (C₃F₇OCH₃),perfluorobutyl methyl ether (C₄F₉OCH₃), perfluorobutyl ethyl ether(C₄F₉OC₂H₅), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(CF₂HCF₂OCH₂CF₃, manufactured by Asahi Glass Company, Limited, AE-3000),etc.

The content of such other compound is not limited within a range not toremarkably decrease the effects of the present invention, and ispreferably at most 30 mass %, more preferably at most 20 mass %,particularly preferably at most 15 mass % in the workingmedium-containing composition (100 mass %).

<Heat Cycle System>

The heat cycle system of the present invention is a system employing theworking medium of the present invention.

The heat cycle system may, for example, be a Rankine cycle system, aheat pump cycle system, a refrigerating cycle system or a heat transportsystem.

(Refrigerating Cycle System)

As an example of the heat cycle system, a refrigerating cycle systemwill be described.

The refrigerating cycle system is a system wherein in an evaporator, aworking medium removes heat energy from a load fluid to cool the loadfluid thereby to accomplish cooling to a lower temperature.

FIG. 1 is a schematic construction view illustrating an example of arefrigerating cycle system of the present invention. A refrigeratingcycle system 10 is a system generally comprising a compressor 11 tocompress a working medium vapor A to form a high temperature/highpressure working medium vapor B, a condenser 12 to cool and liquefy theworking medium vapor B discharged from the compressor 11 to form a lowtemperature/high pressure working medium C, an expansion valve 13 to letthe working medium C discharged from the condenser 12 expand to form alow temperature/low pressure working medium D, an evaporator 14 to heatthe working medium D discharged from the expansion valve 13 to form ahigh temperature/low pressure working medium vapor A, a pump 15 tosupply a load fluid E to the evaporator 14, and a pump 16 to supply afluid F to the condenser 12.

In the refrigerating cyclic system 10, the following cycle is repeated.

(i) A working medium vapor A discharged from an evaporator 14 iscompressed by a compressor 11 to form a high temperature/high pressureworking medium vapor B.

(ii) The working medium vapor B discharged from the compressor 11 iscooled and liquefied by a fluid F in a condenser 12 to form a lowtemperature/high pressure working medium C. At that time, the fluid F isheated to form a fluid F′, which is discharged from the condenser 12.

(iii) The working medium C discharged from the condenser 12 is expandedin an expansion valve 13 to form a low temperature/low pressure workingmedium D.

(iv) The working medium D discharged from the expansion valve 13 isheated by a load fluid E in an evaporator 14 to form a hightemperature/low pressure working medium vapor A. At that time, the loadfluid E is cooled and becomes a load fluid E′, which is discharged fromthe evaporator 14.

The refrigerating cycle system 10 is a cycle comprising an adiabaticisentropic change, an isenthalpic change and an isobaric change, and thestate change of the working medium may be shown as in FIG. 2, when it isrepresented on a temperature-entropy chart.

In FIG. 2, the AB process is a process wherein adiabatic compression iscarried out by the compressor 11 to change the high temperature/lowpressure working medium vapor A to a high temperature/high pressureworking medium vapor B. The BC process is a process wherein isobariccooling is carried out in the condenser 12 to change the hightemperature/high pressure working medium vapor B to a lowtemperature/high pressure working medium C. The CD process is a processwherein isenthalpic expansion is carried out by the expansion valve 13to change the low temperature/high pressure working medium C to a lowtemperature/low pressure working medium D. The DA process is a processwherein isobaric heating is carried out in the evaporator 14 to have thelow temperature/low pressure working medium D returned to a hightemperature/low pressure working medium vapor A.

In the same manner, the state change of the working medium may be shownas in FIG. 3, when it is represented on a pressure-enthalpy chart.

(Moisture Concentration)

There is a problem of inclusion of moisture in the heat cycle system.Inclusion of moisture may cause freezing in a capillary tube, hydrolysisof the working medium or the lubricating oil, deterioration of materialsby an acid component formed in heat cycle, formation of contaminants,etc. Particularly, the above-described ether lubricating oil, esterlubricating oil and the like have extremely high moisture absorbingproperties and are likely to undergo hydrolysis, and inclusion ofmoisture decreases properties of the lubricating oil and may be a greatcause to impair the long term reliability of a compressor. Further, inan automobile air conditioner, moisture tends to be included from acoolant hose or a bearing of a compressor used for the purpose ofabsorbing vibration. Accordingly, in order to suppress hydrolysis of thelubricating oil, it is necessary to suppress the moisture concentrationin the heat cycle system. The moisture concentration of the workingmedium in the heat cycle system is preferably at most 100 ppm, morepreferably at most 20 ppm.

As a method of suppressing the moisture concentration in the heat cyclesystem, a method of using a desiccating agent (such as silica gel,activated aluminum or zeolite) may be mentioned. The desiccating agentis preferably a zeolite desiccating agent in view of chemical reactivityof the desiccating agent and the working medium, and the moistureabsorption capacity of the desiccating agent.

The zeolite desiccating agent is, in a case where a lubricating oilhaving a large moisture absorption as compared with a conventionalmineral lubricating oil is used, preferably a zeolite desiccating agentcontaining a compound represented by the following formula (1) as themain component in view of excellent moisture absorption capacity.

M_(2/n)O.Al₂O₃.xSiO₂.yH₂O  (1)

wherein M is a group 1 element such as Na or K or a group 2 element suchas Ca, n is the valence of M, and x and y are values determined by thecrystal structure. The pore size can be adjusted by changing M.

To select the desiccating agent, the pore size and the fracture strengthare important.

In a case where a desiccating agent having a pore size larger than themolecular size of the working medium is used, the working medium isadsorbed in the desiccating agent and as a result, chemical reactionbetween the working medium and the desiccating agent will occur, thusleading to undesired phenomena such as formation of non-condensing gas,a decrease in the strength of the desiccating agent, and a decrease inthe adsorption capacity.

Accordingly, it is preferred to use as the desiccating agent a zeolitedesiccating agent having a small pore size. Particularly preferred issodium/potassium type A synthetic zeolite having a pore size of at most3.5 Å. By using a sodium/potassium type A synthetic zeolite having apore size smaller than the molecular size of the working medium, it ispossible to selectively adsorb and remove only moisture in the heatcycle system without adsorbing the working medium. In other words, theworking medium is less likely to be adsorbed in the desiccating agent,whereby heat decomposition is less likely to occur and as a result,deterioration of materials constituting the heat cycle system andformation of contaminants can be suppressed.

The size of the zeolite desiccating agent is preferably from about 0.5to about 5 mm, since if it is too small, a valve or a thin portion inpipelines may be clogged, and if it is too large, the drying capacitywill be decreased. Its shape is preferably granular or cylindrical.

The zeolite desiccating agent may be formed into an optional shape bysolidifying powdery zeolite by a binding agent (such as bentonite). Solong as the desiccating agent is composed mainly of the zeolitedesiccating agent, other desiccating agent (such as silica gel oractivated alumina) may be used in combination.

The proportion of the zeolite desiccating agent based on the workingmedium is not particularly limited.

(Chlorine Concentration)

If chlorine is present in the heat cycle system, it has adverse effectssuch as formation of a deposit by reaction with a metal, abrasion of thebearing, and decomposition of the working medium or the lubricating oil.

The chlorine concentration in the heat cycle system is preferably atmost 100 ppm, particularly preferably at most 50 ppm by the mass ratiobased on the working medium.

(Non-Condensing Gas Concentration)

If non-condensing gas is included in the heat cycle system, it hasadverse effects such as heat transfer failure in the condenser or theevaporator and an increase in the working pressure, and it is necessaryto suppress its inclusion as far as possible. Particularly, oxygen whichis one of non-condensing gases reacts with the working medium or thelubricating oil and promotes their decomposition.

The non-condensing gas concentration is preferably at most 1.5 vol %,particularly preferably at most 0.5 vol % by the volume ratio based onthe working medium, in a gaseous phase of the working medium.

Examples

Now, the present invention will be described in further detail withreference to Examples. However, it should be understood that the presentinvention is by no means restricted to such specific Examples.

(Evaluation of Refrigerating Cycle Performance)

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated as the cycle performance (thecapacity and the efficiency) in a case where a working medium wasapplied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14, the averagecondensing temperature of the working medium in a condenser 12, thesupercooling degree of the working medium in the condenser 12, and thedegree of superheat of the working medium in the evaporator 14,respectively. Further, it was assumed that there was no pressure loss inthe equipment efficiency and in the pipelines and heat exchanger.

The refrigerating capacity Q and the coefficient of performance η areobtained from the following formulae (2) and (3) using the enthalpy h ineach state (provided that a suffix attached to h indicates the state ofthe working medium).

Q=h _(A) −h _(D)  (2)

η=refrigerating capacity/compression work=(h _(A) −h _(D))/(h _(B) −h_(A))  (3)

The coefficient of performance means the efficiency in the refrigeratingcycle system, and a higher coefficient of performance means that ahigher output (refrigerating capacity) can be obtained by a smallerinput (electric energy required to operate a compressor).

Further, the refrigerating capacity means a capacity to cool a loadfluid, and a higher refrigerating capacity means that more works can bedone in the same system. In other words, it means that with a workingmedium having a larger refrigerating capacity, the desired performancecan be obtained with a smaller amount, whereby the system can bedownsized.

The thermodynamic properties required for calculation of therefrigerating cycle performance were calculated based on the generalizedequation of state (Soave-Redlich-Kwong equation) based on the law ofcorresponding state and various thermodynamic equations. If acharacteristic value was not available, it was calculated employing anestimation technique based on a group contribution method.

Example 1

The refrigerating cycler performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where HFO-1132(Z)and HFO-1132(E) in a proportion as identified in Table 1 were applied asa working medium to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 1.

TABLE 1 Relative performance (based on HFC-134a) [—] HFO-1132(Z)HFO-1132(E) Refrigerating Coefficient of [mass %] [mass %] capacityperformance 0 100 1.022 1.358 20 80 1.022 1.368 40 60 1.022 1.376 60 401.021 1.383 80 20 1.020 1.389 100 0 1.020 1.393

From the results in Table 1, it was confirmed that there was no distinctdifference among cases where HFO-1132(Z) and HFO-1132(E) were used aloneand a case where they were used in combination.

Example 2

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(Z) and a HFC as identified in Table 2 wasapplied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a, the relativeperformance (each working medium/HFC-134a) of the refrigerating cycleperformance (the refrigerating capacity and the coefficient ofperformance) of each working medium based on HFC-134a was obtained. Theresults of each working medium are shown in Table 2.

TABLE 2 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFC- 134a) [—] HFO- HFC- 134a) [—] 1132(Z) 125 Coefficientof Refrigerating 1132(Z) 134a Coefficient of [mass %] [mass %]performance capacity [mass %] [mass %] performance 0 100 0.795 1.517 0100 1.000 20 80 0.864 1.635 20 80 0.992 40 60 0.924 1.641 40 60 0.994 6040 0.968 1.583 60 40 1.004 80 20 0.998 1.495 80 20 1.012 100 0 1.0201.393 100 0 1.020 Relative performance Relative performance (based onHFC- (based on HFC- 134a) [—] HFO- HFC- 134a) [—] Refrigerating 1132(Z)32 Coefficient of Refrigerating capacity [mass %] [mass %] performancecapacity 1.000 0 100 0.918 2.518 1.186 20 80 0.920 2.422 1.310 40 600.932 2.243 1.381 60 40 0.954 2.003 1.404 80 20 0.989 1.732 1.393 100 01.020 1.393

From the results in Table 2, it was confirmed that the refrigeratingcapacity of HFO-1132(Z) could be improved by adding HFC-125 or HFC-32 toHFO-1132(Z). Further, by addition of HFC-134a, the refrigeratingcapacity could be maintained without a remarkable decrease of thecoefficient of performance.

Example 3

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(E) and a HFC as identified in Table 3 wasapplied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 3.

TABLE 3 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFC- 134a) [—] HFO- HFC- 134a) [—] 1132(E) 125 Coefficientof Refrigerating 1132(E) 134a Coefficient of [mass %] [mass %]performance capacity [mass %] [mass %] performance 0 100 0.795 1.517 0100 1.000 20 80 0.859 1.616 20 80 0.989 40 60 0.918 1.613 40 60 0.991 6040 0.964 1.550 60 40 1.001 80 20 0.997 1.460 80 20 1.012 100 0 1.0221.358 100 0 1.022 Relative performance Relative performance (based onHFC- (based on HFC- 134a) [—] HFO- HFC- 134a) [—] Refrigerating 1132(E)32 Coefficient of Refrigerating capacity [mass %] [mass %] performancecapacity 1.000 0 100 0.918 2.518 1.177 20 80 0.921 2.410 1.293 40 600.934 2.220 1.356 60 40 0.958 1.974 1.372 80 20 0.988 1.689 1.358 100 01.022 1.358

From the results in Table 3, it was confirmed that the refrigeratingcapacity of HFC-1132(E) could be improved by adding HFC-125 or HFC-32 toHFC-1132(E). Further, by addition of HFC-134a, the refrigeratingcapacity could be maintained without a remarkable decrease of thecoefficient of performance.

Example 4

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFC-1132(Z) and a HFC as identified in Table 4 or 5was applied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Tables 4 and5.

TABLE 4 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFO- 134a) [—] HFO- HFO- 134a) [—] 1132(Z) 1225ye(E)Coefficient of Refrigerating 1132(Z) 1225ye(Z) Coefficient ofRefrigerating [mass %] [mass %] performance capacity [mass %] [mass %]performance capacity 0 100 1.024 0.663 0 100 1.005 0.767 20 80 1.0190.921 20 80 1.004 1.014 40 60 1.014 1.109 40 60 1.005 1.183 60 40 1.0161.248 60 40 1.012 1.297 80 20 1.019 1.340 80 20 1.017 1.362 100 0 1.0201.393 100 0 1.020 1.393

TABLE 5 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFO- 134a) [—] HFO- HFO- 134a) [—] 1132(Z) 1234ze(E)Coefficient of Refrigerating 1132(Z) 1243zf Coefficient of Refrigerating[mass %] [mass %] performance capacity [mass %] [mass %] performancecapacity 0 100 0.996 0.752 0 100 0.995 0.978 20 80 0.995 0.986 20 800.997 1.135 40 60 0.998 1.161 40 60 1.002 1.252 60 40 1.007 1.288 60 401.009 1.333 80 20 1.015 1.362 80 20 1.015 1.377 100 0 1.020 1.393 100 01.020 1.393

From the results in Tables 4 and 5, it was confirmed that HFO1132(Z) hada higher refrigerating capacity as compared with conventional HFO.Further, by combination of HFO-1132(Z) and HFO-1225ye(E) orHFO-1225ye(Z), the coefficient of performance could be maintainedwithout a remarkable decrease of the refrigerating capacity.

Example 53

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(E) and a HFC as identified in Table 6 or 7was applied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Tables 6 and7.

TABLE 6 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFO- 134a) [—] HFO- HFO- 134a) [—] 1132(E) 1225ye(E)Coefficient of Refrigerating 1132(E) 1225ye(Z) Coefficient ofRefrigerating [mass %] [mass %] performance capacity [mass %] [mass %]performance capacity 0 100 1.024 0.663 0 100 1.005 0.767 20 80 1.0160.914 20 80 1.000 1.005 40 60 1.010 1.093 40 60 1.000 1.166 60 40 1.0121.224 60 40 1.008 1.271 80 20 1.018 1.309 80 20 1.016 1.330 100 0 1.0221.358 100 0 1.022 1.358

TABLE 7 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HFO- 134a) [—] HFO- HFO- 134a) [—] 1132(E) 1234ze(E)Coefficient of Refrigerating 1132(E) 1243zf Coefficient of Refrigerating[mass %] [mass %] performance capacity [mass %] [mass %] performancecapacity 0 100 0.996 0.752 0 100 0.995 0.978 20 80 0.992 0.978 20 800.994 1.126 40 60 0.993 1.145 40 60 0.998 1.235 60 40 1.002 1.263 60 401.005 1.308 80 20 1.013 1.331 80 20 1.013 1.347 100 0 1.022 1.358 100 01.022 1.358

From the results in Tables 6 and 7, it was confirmed that HFO1132(E) hada higher refrigerating capacity as compared with conventional HFO.Further, by combination of HFO-1132(E) and HFO-1225ye(E) orHFO-1225ye(Z), the coefficient of performance could be maintainedwithout a remarkable decrease of the refrigerating capacity.

Example 6

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(E) and a hydrocarbon as identified in Table 8was applied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 8.

TABLE 8 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- 134a) [—] HFO- 134a) [—] 1132(E) Isobutane Coefficient ofRefrigerating 1132(E) Butane Coefficient of [mass %] [mass %]performance capacity [mass %] [mass %] performance 0 100 1.038 0.540 0100 1.065 20 80 1.039 0.670 20 80 1.063 40 60 1.040 0.816 40 60 1.067 6040 1.034 0.979 60 40 1.055 80 20 1.026 1.165 80 20 1.034 90 10 1.0251.265 90 10 1.027 92 8 1.024 1.284 92 8 1.026 94 6 1.024 1.303 94 61.026 96 4 1.023 1.322 96 4 1.025 98 2 1.023 1.340 98 2 1.024 100 01.022 1.358 100 0 1.022 Relative performance Relative performance (basedon HFC- (based on HFC- 134a) [—] HFO- 134a) [—] Refrigerating 1132(E)Propane Coefficient of Refrigerating capacity [mass %] [mass %]performance capacity 0.393 0 100 0.977 1.340 0.516 20 80 0.977 1.3910.666 40 60 0.980 1.432 0.841 60 40 0.987 1.453 1.060 80 20 1.001 1.4361.201 90 10 1.010 1.407 1.232 92 8 1.012 1.399 1.263 94 6 1.015 1.3901.294 96 4 1.017 1.380 1.326 98 2 1.020 1.370 1.358 100 0 1.022 1.358

From the results in Table 8, it was confirmed that the refrigeratingcapacity of HFO-1132(E) could be improved by adding propane toHFO-1132(E). Further, it was confirmed that by addition of isobutane orbutane, the coefficient of performance was improved, and the decrease ofthe refrigerating capacity could be suppressed up to an addition amountof about 20 mass %.

Example 7

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(Z) and a hydrocarbon as identified in Table 9was applied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 9.

TABLE 9 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- 134a) [—] HFO- 134a) [—] 1132(Z) Isobutane Coefficient ofRefrigerating 1132(Z) Butane Coefficient of [mass %] [mass %]performance capacity [mass %] [mass %] performance 0 100 1.038 0.540 0100 1.065 20 80 1.042 0.673 20 80 1.065 40 60 1.044 0.824 40 60 1.070 6040 1.038 0.992 60 40 1.058 80 20 1.029 1.188 80 20 1.035 90 10 1.0261.293 90 10 1.027 92 8 1.025 1.314 92 8 1.026 94 6 1.024 1.334 94 61.025 96 4 1.022 1.354 96 4 1.023 98 2 1.021 1.374 98 2 1.021 100 01.020 1.393 100 0 1.020 Relative performance Relative performance (basedon HFC- (based on HFC- 134a) [—] HFO- 134a) [—] Refrigerating 1132(Z)Propane Coefficient of Refrigerating capacity [mass %] [mass %]performance capacity 0.393 0 100 0.977 1.340 0.518 20 80 0.979 1.3970.672 40 60 0.984 1.446 0.851 60 40 0.991 1.475 1.079 80 20 1.003 1.4661.226 90 10 1.011 1.440 1.259 92 8 1.012 1.432 1.292 94 6 1.014 1.4241.325 96 4 1.016 1.415 1.359 98 2 1.018 1.404 1.393 100 0 1.020 1.393

From the results in Table 9, it was confirmed that the refrigeratingcapacity of HFC-1132(Z) could be improved by adding propane toHFO-1132(Z). Further, it was confirmed that by addition of isobutane orbutane, the coefficient of performance was improved, and the decrease ofthe refrigerating capacity could be suppressed up to an addition amountof about 20 mass %.

Example 8

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFC-1132(Z) and a HCFC as identified in Table 10 wasapplied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 10.

TABLE 10 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HCFO- 134a) [—] HFO- HCFO- 134a) [—] 1132(Z) 1224ydCoefficient of Refrigerating 1132(Z) 1122 Coefficient of Refrigerating[mass %] [mass %] performance capacity [mass %] [mass %] performancecapacity 0 100 1.061 0.357 0 100 1.099 0.526 20 80 1.061 0.638 20 801.078 0.729 40 60 1.043 0.863 40 60 1.058 0.909 60 40 1.022 1.056 60 401.038 1.077 80 20 1.020 1.242 80 20 1.027 1.242 90 10 1.021 1.324 90 101.023 1.321 92 8 1.021 1.338 92 8 1.022 1.336 94 6 1.021 1.353 94 61.022 1.350 96 4 1.020 1.367 96 4 1.021 1.365 98 2 1.020 1.380 98 21.020 1.379 100 0 1.020 1.393 100 0 1.020 1.393

From the results in Table 10, it was confirmed that the coefficient ofperformance was increased without an extreme decrease of therefrigerating capacity of HFO-1132(Z), by adding HCFO to HFO-1132(Z).

Example 9

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where a workingmedium comprising HFO-1132(E) and a HCFO as identified in Table 11 wasapplied to a refrigerating cycle system 10 shown in FIG. 1.

Evaluation was carried out by setting the average evaporationtemperature of the working medium in an evaporator 14 to be 0° C., theaverage condensing temperature of the working medium in a condenser 12to be 50° C., the supercooling degree of the working medium in thecondenser 12 to be 5° C., and the degree of superheat of the workingmedium in the evaporator 14 to be 5° C.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 11.

TABLE 11 Relative performance Relative performance (based on HFC- (basedon HFC- HFO- HCFO- 134a) [—] HFO- HCFO- 134a) [—] 1132(E) 1224ydCoefficient of Refrigerating 1132(E) 1122 Coefficient of Refrigerating[mass %] [mass %] performance capacity [mass %] [mass %] performancecapacity 0 100 1.061 0.357 0 100 1.099 0.526 20 80 1.058 0.633 20 801.078 0.724 40 60 1.040 0.852 40 60 1.059 0.899 60 40 1.021 1.038 60 401.040 1.061 80 20 1.020 1.215 80 20 1.029 1.217 90 10 1.022 1.293 90 101.026 1.291 92 8 1.022 1.307 92 8 1.025 1.305 94 6 1.022 1.320 94 61.025 1.318 96 4 1.023 1.333 96 4 1.024 1.332 98 2 1.022 1.346 98 21.023 1.345 100 0 1.022 1.358 100 0 1.022 1.358

From the results in Table 11, it was confirmed that the coefficient ofperformance was increased without an extreme decrease of therefrigerating capacity of HFC-1132(E), by adding HCFC to HFO-1132(E).

Example 10

The refrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) was evaluated in a case where HFC-1132(E),FIFO-1132(Z) or 1,1-difluoroethylene (HFC-1132a) was applied as aworking medium to a refrigerating cycle system 10 shown in FIG. 1.

The evaporation temperature of the working medium in an evaporator 14,the condensing temperature of the working medium in a condenser 12, thesupercooling degree of the working medium in the condenser 12 and thedegree of superheat of the working medium in the evaporator 14 weretemperatures as identified in Table 12.

Based on the refrigerating cycle performance of HFC-134a in Example 2,the relative performance (each working medium/HFC-134a) of therefrigerating cycle performance (the refrigerating capacity and thecoefficient of performance) of each working medium based on HFC-134a wasobtained. The results of each working medium are shown in Table 12.

TABLE 12 Relative performance (based on HFC-134a) [—] EvaporationCondensing Degree of Supercooling HFO-1132(Z) HFO-1132(E) HFO-1132atemperature temperature superheat degree Coefficient of RefrigeratingCoefficient of Refrigerating Coefficient of Refrigerating [° C.] [° C.][° C.] [° C.] performance capacity performance capacity performancecapacity −40 10 5 5 0.987 1.619 1.001 1.582 0.800 7.271 −30 20 5 5 0.9951.543 1.006 1.507 — — −20 30 5 5 1.004 1.481 1.012 1.446 — — −10 40 5 51.012 1.432 1.017 1.397 — — 0 50 5 5 1.020 1.393 1.022 1.358 — — 10 60 55 1.029 1.364 1.029 1.328 — — 20 70 5 5 1.040 1.346 1.039 1.308 — — 3080 5 5 1.057 1.340 1.053 1.300 — — 40 90 5 5 1.087 1.355 1.079 1.310 — —

From the results in Table 12, it was confirmed that HFO-1132 had ahigher coefficient of performance as compared with FIFO-1132a. Here,HFO-1132a has a too low critical temperature, whereby a supercriticalcycle will form at a condensing temperature of at least 20° C., andaccordingly evaluation was not conducted.

INDUSTRIAL APPLICABILITY

The working medium of the present invention is useful as a workingmedium for heat cycle such as a coolant for a refrigerator, a coolantfor an air conditioner, a working fluid for power generation system(such as exhaust heat recovery power generation), a working medium for alatent heat transport apparatus (such as a heat pipe) or a secondarycooling medium.

This application is a continuation of PCT Application No.PCT/JP2012/062844, filed on May 18, 2012, which is based upon and claimsthe benefit of priority from Japanese Patent Application No. 2011-112416filed on May 19, 2011. The contents of those applications areincorporated herein by reference in its entirety.

REFERENCE SYMBOL

-   -   10: Refrigerating cycle system

1-13. (canceled)
 14. A working medium for heat cycle, comprising:1,2-difluoroethylene, at least one hydrofluoroolefin other than1,2-difluoroethylene, and optionally, at least one hydrofluorocarbon.15. The working medium of claim 14, comprising the at least onehydrofluorocarbon.
 16. The working medium of claim 15, wherein the atleast one hydrofluorocarbon is difluoromethane.
 17. The working mediumof claim 14, comprising at least 60 mass %, based on the mass of theworking medium, of the 1,2-difluoroethylene.
 18. The working medium ofclaim 15, comprising from 1 to 30 mass %, based on the mass of theworking medium, of the at least one hydrocarbon.
 19. The working mediumof claim 18, wherein the at least one hydrocarbon is selected from thegroup consisting of propane, propylene, cyclopropane, butane, isobutane,pentane, and isopentane.
 20. The working medium of claim 14, comprisingfrom 1 to 99 mass %, based on the mass of the working medium, ofdifluoromethane.
 21. The working medium of claim 14, comprising from 1to 60 mass %, based on the mass of the working medium, ofdifluoromethane.
 22. The working medium of claim 14, comprisingdifluoromethane and pentafluoroethane.
 23. The working medium of claim14, further comprising at least one compound selected from the groupconsisting of a hydrochlorofluoroolefin or a chlorofluoroolefin.
 24. Theworking medium of claim 23, wherein a total content of thehydrochlorofluoroolefin and the chlorofluoroolefin is from 1 to 60 mass%, based on the mass of the working medium.
 25. A heat cycle system,comprising the working medium according to claim 14, an evaporator, acompressor, a condenser, an expansion valve, and a load fluid.
 26. Theworking medium of claim 14, wherein the 1,2-difluoroethylene is(E)-1,2-difluoroethylene.